Patient handling mattresses are known in the art which include at least two flexible material sheets, that together define a plenum chamber, with at least one sheet being perforated with small pinholes over at least a central surface area, and which open up directly to the interior of the plenum chamber. Such prior art mattresses are used by arranging the perforated sheet so that it faces an underlying fixed, generally planar support surface, such as a floor or table. When the mattress is charged with pressurized air, the escape of air under pressure through the pinholes acts initially to jack a load placed upon the mattress above the perforated flexible sheet, and thereby creates an air bearing of relatively small height between the underlying fixed, generally planar support surface and the perforated flexible sheet.
For example, in U.S. Pat. No. 4,517,690, issued to Wegener, an air pallet is disclosed that is formed from upper and lower thin flexible film sheets sealed at their edges to form a plenum chamber. Wegener's air pallet functions to move a load with minimal friction over an underlying generally planar fixed support surface. The bottom thin flexible material sheet is perforated by small diameter perforations such as pin holes at the load imprint area.
In U.S. Pat. No. 5,561,873, issued to Weedling, provides an inflatable flexible pallet within which an array of structurally interrelated inflatable chambers are formed to support a load when inflated. The flexible pallet is configured to resist lateral and longitudinal shrinkage of the load support surface, as well as ballooning and hot dogging. Rotational instability is also reduced by providing a greater load surface support area.
In U.S. Pat. No. 6,073,291, issued to Davis, an inflatable medical patient transfer apparatus is disclosed that has a combination of transverse partition members and a raised perimeter section to reduce deleterious ballooning and uneven inflation as well as quick emergency deflation. Additional differentially inflatable patient rolling chambers are disclosed on the top of the transfer apparatus to provide assistance to medical personnel in beginning to roll patients reclining or lying upon the transfer apparatus, particularly in a deflated condition on a hospital bed.
All of the foregoing devices have suffered from an inability to be used during X-ray imaging of a patient lying upon the mattress. Proper X-ray imaging requires that the patient remain motionless during the exposure. Prior art transfer mattresses tend to drift or move, and are easily moved by even small perturbations. Thus, they are required to be deflated prior to effecting X-ray imaging of the patient. Unfortunately, when deflated, the patient is forced to lie upon a very stiff table that can be quite uncomfortable for heavier patients.
Many of the foregoing devices also suffer from the fact that when uninflated they tend to bunch causing photo images to appear upon the x-ray exposures that mask underlying physiological features of the patient. There is a continuing need to be able to easily and safely x-ray a patient on an inflated transfer mattress.